Pulsed nuclear magnetic resonance (NMR) will be used to study nuclear spin relaxation, molecular diffusion, and molecular interactions in model membranes and in thermotropic liquid crystals. Lateral diffusion rates of lipids in oriented lipid/D2O multilayers will be studied using techniques developed and applied previously. The effects on lipid diffusion of the addition of ions (such as Ca++) and of drugs (alamethicin, valinomycin) to the multilayers will be studied. Mixed lipid systems which show phase separations will be studied using protein diffusion and C-13 NMR techniques. This work will focus on conformational changes accompanying separation. Data from the study will be relavant to membrane dynamics, lipid/drug interactions, health problems related to plasma membrane transport deficiencies, and theories of membrane and liquid crystal structures.